13 Jul
2017
13 Jul
'17
9:29 p.m.
Yeah, Sebastian is quite right. CANCELs do make for an especially
challenging case, since they are hop-by-hop. Kamailio has to have some
transaction state in order to have an idea of where to relay them.
A good business process is to have two Kamailio instances, tried by all
gateways on all sides if the primary is unavailable (whether by means of
SRV or just statically configured secondary gateway entries) and some
option, set externally at runtime (for example, using $shv() shared
variables), which causes Kamailio to refuse further calls. Existing
calls would drain off the system, new calls would fail over to the other
Kamailio, and then you can restart it.
On Thu, Jul 13, 2017 at 06:22:55PM +0000, Samuel F. wrote:
Thank you for the responses! As a follow up question,
how do companies with large loads on their Kamailios handle restarts especially
considering the CANCELs?
What is a good (business) process to restart a Kamailio without incurring any
interruptions at all? What other components in the infrastructure would be in place and
which ones are in use in the wild?
// Samuel
________________________________
From: sr-users <sr-users-bounces(a)lists.kamailio.org> on behalf of Sebastian Damm
<damm(a)sipgate.de>
Sent: Thursday, July 13, 2017 2:39:39 PM
To: Kamailio (SER) - Users Mailing List
Subject: Re: [SR-Users] What happens to calls when Kamailio restarts?
Hi,
On Wed, Jul 12, 2017 at 11:53 AM, Alex Balashov
<abalashov(a)evaristesys.com> wrote:
All SIP messages passing through the proxy can be
forwarded statelessly
and based on properties of the SIP message alone.
There's one thing that could happen: Calls that get cancelled after a
restart, could possibly keep on ringing on the far end. At least if
you check for an active transaction in your kamailio config.
if (!t_check_trans()) {
sl_send_reply("481", "Call/Transaction does not exist");
xlog("L_ERR", "CANCEL: found no matching transaction F=$fu T=$tu
R=$ru\n");
return;
}
And if you do some sort of random dispatching, CANCELs could end up on
a different gateway.
But other than that, a restart shouldn't cause much trouble.
Especially in-call requests get routed by Route headers only.
Regards,
Sebastian
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